Refractory brick having spacer plates



y 7 5 R. P. HEUER ET AL 2,791,116

REFRACTORY BRICK HAVING SPACER PLATES Filed Aug. 19, 1953 INVENTORS-Russell fiearce He we) REFRACTORY BRICK nzwmosrhcnn rmrnsf Russell Pearce Hel er, Bryn-Ma'wr, and Mervin Adrian Fay; Nat-berth; Pal,assig'lib'rs to" Geilei'i'alf Refraetories' ion'ipaiiy, Philadelphia,Pa.', a" coriiern'tiowof Perm sylvania' Application-August 19;1'9ss,-seria1 Not-315x94 sedans: ori -72 3's)" t-r'fmtigh'eur.

fiesenliih'g in iu'u'stratisn btm n'ft ih lhiritatien ann referring tothe drawings:

Inahe construetien of many types'o furnace's to 'be new at high:temeeratnreg. such! as open hearth: 'steel it is desirable to usesuspended"- refraietony n this puhpose consist oh the various Basie ref"ates of win the nrost widelwuse'dflaite mage nests, chrome rrragnesiaand Inagnesiawhrome: -It= is custemary' to lay-5 the" ibri'cld with"tntit'lizab'le metal-liosp'ac'ers in the joints. Fr'eqdentlys'"suchbasic brick am used without previous kiln firingzzandiin su'eh casesthe metitiiic spacersar" d Ev service of this cnaraetr; faiwre df tlierefractor isprirnarily-Byspalling'a yor th atth nst-end duetd thetemperature changes which the hottest part of -theliriek-eiiperienceinthe'cycle'of interthittent" tion Omerurnacez- The crrteinperarure an the brick a exiiand and contractrap'idly, ana' eventaatly the briek fracture andshall ofi aloh'iplanes Whi parallel: totheexposed" faces or the lb rick" add about"one-inch-from the hot e'n'd.This-spa11tng7eaues prematuhe f-ailaret p u 7 In: a' refractdry rcofi-or-wall, eaeh brickhasits hot end exposed to": the i'ntei'ior of the?furnace; while' the sides 'pa'r allel to 'tlie rnaioiaxis of the' briclextend outwardly from the f interior and are protected from--the- Y mayexhibit a temperatur of 000 supported wall: constiuetienst- Therfrazcto- .st'eet is mgr'pea fiswanwpes heaith steel fui nacet A2,791,116 Patented May 7, 1957 l' gi adie'n 't sheave-vans along thelongitudinal axis of the brick;

Afterthe" fur r1ace"is" tapped, the tuma'ce d'o'oi's are open-en,tli'efhel" is shut oil and a'large quantityv of cold char e is placedinthefurnace As a result the hot end of rick'coolsrapidly and itstemperaturernay fall to 1000" FL Sincethe cooling is relativelyrapidmos-t'of the-temperature change is confined to the'hot' endof thebrick, ahdatsorne" interior'point there is relativelylittle loss iijit'm'perstnre I I fifter charging of the furn'a'ce is c'ornpleted, thefuel is again silp plie'd' to the furnace andthe ho't' end: of" thebrick rise tempe atureun il the gradient formerly eXi's'ting is againestablishedi Thisf-operatingcycle is" re peated a g'ai'n andag'ain. Thebrick arethus subjected to repeated straiiis andifinally' fracturedevelops parallel ti) the Hof'eifd aiid":the hot end: sgalls oif. Anewhot end is thus established; and thisissubjec'ted' to similartieiitineiit aiid 'gi'adually'the brick are des't'royedi If we considerthe brick as divided into elements parallel to the longitudinal axisandparallel to'one andtfieh-it willbe' evident that the adherence ofe'achele merit"- tb it's" n'eighhdr tends to set up tensile" stressesaerbs the4fot face of-the which tend to increase the tliick iie'ss of'tfie individual elements when th'ehotface refraetorfcann'ot stan'd,whereupon a; crack will result 0 the hot end-L The defori'rratidnoftheele'nients' 'iiek i1iay"ei c eed the strain which the refractory ofstanding and this wnr produce cracks parthe-T face:

he 'st'r'ain'ss'et up heating'and cooling;

The spacers are usually made of ordina fy 10W car-lion steel,althou'glfthey'can be n'iade of -any oki'diiz' able' construet-idnrnetal or alloy which will operate at the rempe ie of tlie' hot end ofthe refracto'ry.- It'will'be evi-den" of courseth'atthespacers need notbe 'oXidiiable atreonr ternperature so long as 7 they oxidize at furnacetemperature, and th'erefore'stainless steel, such as the 18% ehrom-iuin;8% nickel-grade or the"1'6%" chromium grade" or 'otlter alloys ofiron'and chromium" may be used.

The' heafiof thefurn'ace oxidizesthe spacers at the hottest pant of thebrick and the iron or other metallic oxiderfermed reacts-with the basicmaterial present 'in the refr-aetory,--suitably magnesia'or impuritiesin chro ore; The resultant product welds together to toxin: a rnonolith-ic structure which definitely resists cracl -fdrmatiofi.

Oui studies indicate that the-strain set up in the surfaeei'ofthe b rickdue to" heating; and cooling are "greater ie the-aransverse dirnensionsof the brick are greater.

We have discovered" th'at improved resistance to spall ing is obtainedby irnbedding in the brick at the time of molding; aplurality ofoxidizable'metallic spacer plates Wliiclfiare placed'in a plane'orplanes" parallel tothe major axis of the brickfand preferablyapproximately parallel to oneof the faces of the brick whi'chextends-longitudinally in the' 'furnacei thereliy subdividing:the'brickintocor'rioldedt cells-ofi srn'aller" dimensions, which can'-be heated and codled with 1ess*strain-- atthe-outer surface. The

same mysterious action of the spacer plate which minimizes the crackformation when the plate is located at the edge of the brick likewiseminimizes the crack formation at the edges of the cells within thebrick. Therefore, spalling resistance is decreased due to a combinationof the cellular effect on account of reduced dimensions subjected tostrain, and the skin effect exerted by the oxidizable metallic spacersubdividing the cells.

While the partition wall between the cells should extend a major portionof the distance across the brick at the hot end (and most desirably atleast of each distance) it will be understood that there may be someremaining cross connection between the refractory where the partitiondoes not fully extend across the brick. Likewise while the cell shouldrun the major portion of the length of the brick, it will be understoodthat considerable benefit will be evident if the partition is located atthe hot end and extends for a distance of even two or three inches fromthe hot end. Naturally for best results the cells should be separatedfor the major portion of the length of the brick beginning at thehotend.

The brick mix employed may, for example, be magnesia or refractorymaterial high in magnesia, such as dead burned magnesite or electricallyfused magnesia. It is important that the refractory material be of abasic nature, since certain refractories such as silica would react withthe metallic spacers when they oxidize and would form fusible slags,destroying the roof. Chromite may be usedinstead of part of the materialhigh in magnesia. For example mixtures of chromite with magnesia,containing for instance 75% of chromite and 25% of dead burnedmagnesite, may be used.

The amount of chromite present may be decreased for example to acomposition containing 25% chromite and 75 of dead burned magnesite. Anyother suitable basic refractory composition may be employed.

Bonding substances should preferably be added to secure bond withoutkiln firing. Organic binders such as sulphitepitch, dextrin, glue, gumarabic or inorganic binders such as water solutions of magnesiumsulphate, magnesium chloride, sodium dichromate, sodium silicate and thelike may be used. The amount of binder used should be suflicient to forma brick which is mechanically strong without kiln firing. Normally thebinder will be of the order of one percent on the weight of the brick,and will seldom exceed two percent, and should never exceed fivepercent.

The pressure of molding the brick will in any case exceed 1000 poundsper square inch (70.3 kilograms per square centimeter), and preferablyexceed ,5000 pounds per square inch (351.5 kilograms per squarecentimeter) and will most desirably exceed 10,000 pounds per square inch(703 kilograms per square centimeter).

Where reference is made herein to a brick it is intended to include anystandard refractory shape as well as any suitable block or shapeprovided with any suitable contour or attachment to engage a suitablehanger or support if any.

Figure 1 shows a brick 20 according to the invention, having refractorymaterial 21 which is comolded with a suitably U-shaped metallic spacerplate 22 having a base of the U 23 which is on one longitudinal face ofthe brick and opposing arms of the U 24 and 25 which'are on opposedlongitudinally extending sides of the. brick;

The arms extend desirably the full dimension or at least a major portionof the full dimension of the brick in the direction in which the armsextend away from the base of the U. 1

In order to interlock with the brick, projections or tongues 26 arelanced from the arms and extend inwardly and are comolded in the sidesof the brick.

In the preferred embodiment the side of the brick opposite to the baseof the U is provided with a preferably flat metallic plate 27, whichpreferably extends the full length of the face in the direction of themajor axis of the brick, although it will be understood that it may havesuitable cutouts for a hanger opening or hanger projection if desired.Tongues or projections 28 are suitably lanced or otherwise formed fromthe spacer plate 27 and are embedded by comolding in the refractory.

Internal spacer plates or partition walls 30 of which two are shown inspaced relation extend in the direction from the base of the U 23 towardthe opposing spacer plate 27 and are desirably secured to the base ofthe U as by spot welding at 31. The partition plates or internal plates30 extend parallel to the sides of the U in the form shown, subdividingthe brick in the particular embodiment into external refractory cells 32and 33, beginning at or adjacent to the hot end 34, and internalrefractory cell 35, likewise beginning at or adjacent to the hot end.

The refractory cells formed are desirably equal.

It is not important for the purpose of the present invention whether ornot the partition plates have tongues or interlocks comolded in therefractory similar to the tongues or interlocks 26 and 28.

The partition plates will, where desired, extend the full length of thebrick in the direction of the major axis as shown in Figure 1, but insome cases the partition plates 30' are shortened as shown in Figure 2,so that room will be permitted for a hanger socket at the cold end ofthe brick.

It will be understood that the molding pressure in forming the brick isapplied between the face of the brick located at the base of the U 23and the plate 27 so that the internal plates and the external plates areintimately associated with the refractory by comolding. Thus theinternal plates extend across the major portion of the dimension of thebrick in the direction of molding.

All of the plates comolded with brick are desirably 35 of oxidizablemetal such as steel as already explained.

The spacers and the partition plate are preferably of sheet orplateabout A inch thick, although thicker or thinner spacers may beused. Spacers and partition plates thicker than inch are not recommendedbecause of the tendency of the metal to melt out rather than oxidize,and spacers thinner than ,4 inch are not recommended because theoxidized layer formed is not adequately thick.

The molded brick are desirably dried for about 24 hours, after whichthey are ready for use without kiln drying.

.It will be evident that while the U-shaped plates will be preferred,flat plates on the external faces will some times be desirable.

In view of our invention and disclosure variations and modifications tomeet individual whim or particular need will doubtless become evident toothers skilled in the art, to obtain all or part of the benefits of ourinvention without copying the brick shown, and we, therefore, claim allsuch insofar as they fall within the reasonable spirit and scope of ourclaims.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent is:

1. A basic refractory brick composed of a refractory of the classconsisting of magnesia and mixtures of magnesia and chrome ore, saidbrick having generally parallel opposed outside longitudinal faces and aplurality of spaced oxidizable metallic plates extending in comoldedrelation longitudinally through the interior of the brick transverse tothe intended hot face of the brick and over a major cross section of thebrick in substantially the same direction as said opposed outside faces,said oxidizable metallic plates dividing said refractory into outsideand inside cells between said outside faces of the brick and saidplates, and said plates being adapted to react in the inside of thebrick with the basic refractory and strengthen the refractory of saidcells adjacent to said nesia and chrome ore, having external andinternal refractory cells, comolded external oxidizable metallic platesat opposed longitudinal outside faces of the brick, comolded internaloxidizable metallic plates interposed between said external and internalcells and extending through the interior adjacent to the hot face andextending over a major portion of the cross section of the brick, theexternal and internal plates being adapted to oxidize and the internalplates being adapted to react in the inside of the brick with the basicrefractory and strengthen said external and internal cells.

3. A refractory brick of claim 2, further characterized in that theinternal plates are generally parallel to the external plates.

4. A refractory brick of claim 2, in which the internal plates and theexternal plates are directly interconnected.

5. A refractoly brick of claim 2, in which the internal cells and theexternal cells are of substantially equal size.

6. A basic refractory brick composed of a refractory of the classconsisting of magnesia and mixtures of magnesia and chrome ore, saidbrick having generally parallel opposed outside faces, a plurality ofspaced oxidizable metallic plates extending in comolded relationlongitudinally through the interior of the brick transverse to theintended hot face of the brick and over a major cross section of thebrick in substantially the same direction as said opposed outside faces,and an oxidizable metallic plate extending in comolded relation over alongitudinal face of the brick other than said opposed outsidelongitudinal faces, and extending in a direction perpendicular to saidinternal plates, said oxidizable metallic internal plates dividing saidrefractory into outside and inside cells between said opposed outsidefaces of the brick and said internal plates, and said internal platesbeing adapted to react in the inside of the brick with the basicrefractory and strengthen the refractory of said cells adjacent to saidinternal plates.

References Cited in the file of this patent UNITED STATES PATENTS2,247,376 Heuer July 1, 1941 2,527,063 Heuer Oct. 24, 1950 2,579,050Ramsay Dec. 18, 1951 2,652,793 Heuer Sept. 22, 1953 2,673,373 Heuer Mar.30, 1954

1. A BASIC REFACTORY BRICK COMPOSED OF A REFRACTORY OF THE CLASSCONSISTING OF MAGNESIA AND MIXTURES OF MAGNESIA AND CHROME ORE, SAIDBRICK HAVING GENERALLY PARALLEL OPPOSED OUTSIDE LONGITUDINAL FACES AND APLURALITY OF SPACED OXIDIZABLE METALLIC PLATES EXTENDING IN COMOLDEDRELATION LONGITUDINALLY THROUGH THE INTEIOR OF THE BRICK TRANSVERSE TOTHE INTENDED HOT FACE OF THE BRICK AND OVER A MAJOR CROSS SECTION OF THEBRICK IN SUBSTANTIALLY THE SAME DIRECTION AS SAID OPPOSED OUTSIDE FACES,SAID OXIDIZABLE METALLIC PLATED DIVIDING SAID REFRACTORY INTO OUTSIDEAND INSIDE CELLS BETWEEN SAID OUTSIDE FACES OF THE BRICK AND SAIDPLATES, AND SAID PLATES BEING ADAPTED TO REACT IN THE INSIDE OF THEBRICK WITH THE BASIC REFRACTORY AND STRENGTHEN THE REFRACTORY OF SAIDCELLS ADJACENT TO SAID PLATES.